Method and device for generating hot combustion waste gases

ABSTRACT

A process produces hot combustion waste gases, in particular for a gas turbine system. In a burner, a combustion produces hot combustion waste gases. A portion of the combustion waste gases is branched off and fed to a first inlet of an oxygen separation device. An oxygen-containing gas is fed to a second inlet of the oxygen separation device. The oxygen separation device is provided with at least one oxygen separation means that removes oxygen from the oxygen-containing gas and feeds it to the branched-off waste gas, producing an oxygen-containing gas whose oxygen content has been reduced as well as an oxygen-enriched, branched-off waste gas. The oxygen-enriched, branched-off waste gas and a fuel or a fuel/steam mixture are fed to the burner and form a combustion mixture that burns in the burner while forming the hot combustion waste gases. In order to improve the efficiency of such a method, the burner contains a catalyzer that initiates and/or stabilizes the combustion.

FIELD OF TECHNOLOGY

[0001] The invention relates to a method and to a device for generating hot combustion waste gases, in particular to a gas turbine system having the characteristics of the preamble of Claim 1 or respectively of Claim 4.

STATE OF THE ART

[0002] EP 0 882 486 A1 discloses a device of the above-mentioned type provided with a burner whose outlet side is connected to a waste gas line, from which a return line branches off. In this burner, a combustion that generates hot combustion waste gases takes place. These combustion waste gases exit the burner through the waste gas line, whereby one part of the combustion waste gases is branched off via the return line. The device is provided with an oxygen separation device, the first inlet of which is connected to the return line, and the second inlet of which is connected to a gas supply that provides oxygen-containing gas. The oxygen separation device therefore is supplied with branched-off or returned waste gas via its first inlet, and with oxygen-containing gas, for example concentrated ambient air, via its second inlet. The oxygen separation device contains oxygen separation means, for example an ion transport membrane. These oxygen separation means remove oxygen from the oxygen-containing gas and supply it with the branched off waste gas, so that the oxygen content of the oxygen-containing gas is reduced, and oxygen-enriched, branched-off waste gas is generated. The oxygen separation device is provided with a first outlet for the oxygen-enriched, branched-off waste gas as well as a second outlet for the gas that has been reduced with respect to its oxygen content. An inlet side of the burner is connected to the first outlet of the oxygen separation device as well as to a fuel supply that supplies fuel. In this manner, a combustion mixture that burns in the burner while forming the desired hot combustion waste gases is created no later than in the burner. The combustion gases generated in this manner can be used, in particular, in a gas turbine system in order to generate electrical energy.

[0003] By using such a device or method, it is possible to reduce noxious emissions during energy generation, in particular to significantly reduce CO₂ emissions during the combustion of fossil fuels.

[0004] The core concept of these methods and devices is that pure oxygen is used as an oxidant for the combustion, since this greatly simplifies the waste gas after treatment. The reason for this is that a combustion process with molecular oxygen provides a waste gas that essentially consists only of CO₂ and H₂O. Since oxygen, which is produced in refrigerated plants, is very expensive, new technologies have been developed for oxygen production. Important factors hereby are oxygen separation devices that are provided with a membrane that is conductive for oxygen ions and electrons, a so-called MCM membrane (mixed conducting membrane). Such an MCM membrane has a retention side on which the oxygen-containing is located and a pass-through side on which the gas to be enriched is located. The MCM membrane transports oxygen ions from the retention side to the pass-through side and causes an electron transport from the pass-through side to the retention side. For this purpose, oxygen is removed from the gas on the retention side and is supplied to the gas on the pass-through side. In order to increase the conductivity of such a MCM membrane, it is advantageous to set a relatively high flow speed on the pass-through side in order to keep the oxygen concentration on the pass-through side as low as possible. A high flow speed on the pass-through side results only in a relatively small enrichment of the returned waste gases with oxygen, however, so that this oxygen/waste gas mixture shows only weak reactance and is not suitable for standard combustion methods.

[0005] U.S. Pat. No. 5,976,223 discloses a method and a device for producing carbon dioxide and oxygen. Into a first oxygen separation device working with a MCM membrane, compressed, heated, and oxygen-containing gas is introduced on the retention side. On the pass-through side, a gaseous fuel is supplied that reacts with the added oxygen and forms carbon dioxide. The oxygen-containing gas whose oxygen-content has been reduced is heated by the exothermic reaction taking place hereby. The oxygen-containing gas heated in this manner is then fed to a second oxygen separation device working with an MCM membrane on its retention side. The desired oxygen then collects on the pass-through side of this second oxygen separation device.

[0006] WO 98/55394 describes a method in which an oxygen separation device working with an MCM membrane is used as a burner in order to produce hot combustion waste gases for a gas turbine system. Hereby ambient air is compressed, heated, and fed to the retention side of this membrane reactor. A mixture of returned waste gas and fuel is fed to the retention side. Then oxygen is removed from the fed-in air in the membrane reactor and is fed into the mixture. On the pass-through side, the fuel then reacts with the oxygen on the membrane surface that is coated with an oxidation catalyzer. The resulting hot waste gases are then fed to a turbine.

[0007] WO 98/55208 discloses a further method for the production of hot combustion gases for the operation of a turbine, in which compressed fresh air is heated in a first burner and is fed to the retention side of a oxygen separation device working with an MCM membrane. Returned waste gas is fed together with fuel to a second burner that may be constructed as a catalyzer. The combustion gases generated there are then fed to the pass-through side of the oxygen separation device, where they are enriched with oxygen. The waste gases enriched with oxygen are then fed to a third burner and burned there with fuel in order to generate hot combustion gases that drive a turbine.

DESCRIPTION OF THE INVENTION

[0008] The invention at hand concerns the objective of disclosing for a method or device of the initially mentioned type an embodiment that has a higher efficiency.

[0009] According to the invention, this objective can be realized with a method having the characteristics of Claim 1. The invention is based on the general idea of catalytically initiating or stabilizing, as the case may be, the combustion of the waste gases enriched with oxygen with the added fuel or added fuel/steam mixture. This procedure allows the combustion mixture to react adequately even in the presence of relatively low oxygen concentrations in order to produce the desired hot combustion waste gases. Since this means that a relatively low oxygen content in the combustion mixture will be sufficient, the flow speed of the returned waste gases can be increased on the pass-through side of an oxygen separation device working with an MCM membrane, increasing its efficiency and thus the efficiency of the entire process.

[0010] The objective underlying this invention is also realized with a device according to the characteristics of Claim 4. The invention is hereby based on the general idea of providing the burner with a catalyzer that initiatives or stabilizes the combustion of the combustion mixture. This also creates the possibility of burning combustion waste gases with a relatively low oxygen content in order to generate the desired hot combustion waste gases. As explained above, this makes it possible to increase the efficiency during the production of the hot combustion waste gases. With an integration of the device according to the invention or the method according to the invention into a gas turbine system, the latter's efficiency also can be increased.

[0011] In a further development, a second oxygen separation device may be provided, whereby the non-branched-off or non-returned part of the hot combustion waste gases as well as fuel or fuel/steam mixture are fed to a first inlet of this second oxygen separation device and hereby form a mixture, and whereby the oxygen-containing gas that has been reduced with respect to its oxygen content is fed to a second inlet of this second oxygen separation device, whereby this second oxygen separation device also is provided with oxygen separation means, for example an MCM membrane, that is able to remove yet even more oxygen from the oxygen-containing gas and feed it into the mixture, whereby the mixture on the one hand burns with the oxygen and produces hot combustion waste gases, while on the other hand a gas that has again been reduced with respect to its oxygen content and heated, i.e. oxygen-poor gas, is produced. These measures make it possible to provide both hot combustion waste gas as well as hot, oxygen-poor gas, which can be used, for example, in a following gas turbine system for the production of electricity. Because of the higher starting temperatures that can be achieved, this results overall in a higher efficiency for the overall system.

[0012] In a preferred further development, the catalyzer of the burner can be designed as a metal oxide catalyzer. Suitable metals belong, for example, to the perovskite family, e.g. La_(1−x)Sr_(x)BO₃, whereby the B side contains elements of the transition metals, for example Mn, Fe, Co. Simple metal oxides from Mn or Ce also can be used. Metal oxide catalyzers are characterized by their high heat resistance, but in contrast to noble metal catalyzers require higher inlet temperatures, which in the present case do exist, however.

[0013] Catalyzers with a monolithic carrier and parallel flow channels were found to be advantageous. Such catalyzers are characterized by their relatively low flow resistance. Catalyzers of this type are used, for example, in waste gas cleaning systems of vehicles, in so-called “3-wax catalyzers.”

[0014] In an especially advantageous embodiment, the burner may be connected in a heat-transferring manner with a heat exchanger that heats the oxygen-containing gas prior to its entrance into the oxygen separation device. The heat exchanger, for example, forms the outer sleeve of the burner, achieving an especially high efficiency for the heat exchanger.

[0015] Preferred is a first embodiment in which the oxygen separation device has a first chamber and a second chamber, and in which the oxygen separation means are provided with a membrane, for example an MCM membrane, that separates the two chambers from each other and transports oxygen from one chamber into the other chamber. Particularly advantageous hereby is an embodiment in which the flow passes through both chambers in the same direction and parallel to the membrane. This flow in the same direction makes it possible to create a relatively low temperature profile in the membrane, both parallel to the flow and vertical to it. As a result, thermal loads are reduced.

[0016] Other important characteristics and advantages of the invention can be found in the secondary claims, drawings, and associated description of the drawings

BRIEF DESCRIPTION OF DRAWINGS

[0017] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description. The schematic drawings show in:

[0018]FIG. 1 a block diagram-like principle view of a device according to the invention for a first embodiment,

[0019]FIG. 2 a view as in FIG. 1, but for a second embodiment,

[0020]FIG. 3 a block diagram-like principle view of a gas turbine system containing a device according to the invention,

[0021]FIG. 4 a longitudinal section of a principle view through a burner constructed according to the invention in a first embodiment, and

[0022]FIG. 5 a view as in FIG. 4, but for a second embodiment.

WAYS OF EXECUTING THE INVENTION

[0023] According to FIG. 1, a device 1, here symbolized by a box, is provided with a burner 2, a heat exchanger 3, a compressor 4, and an oxygen separation device 5. This oxygen separation device 5 has as an oxygen separation mean an MCM membrane 6, symbolized here by a dotted line. This MCM membrane 6 divides in the oxygen separation device 5 a first chamber 7 from a second chamber 8, whereby in the first chamber 7 a pass-through side 9, and in the second chamber 8 a retention side 10 is exposed to the membrane 6. In the burner 2, a combustion takes place that produces hot combustion gases 11 that enter on an outlet side 12 of the burner 2 into a waste gas line 13 connected to it. At 14, the desired hot combustion gases 11 are passed out of the device 1.

[0024] From the waste gas line 13, a return line 15 branches off, which is connected to a first inlet 16 of the of the oxygen separation device 5. Through this first inlet 16, branched-off waste gas 17 is able to reach the first chamber 7, i.e. the pass-through side 9 of the membrane 6.

[0025] At 18, oxygen-containing gas 19, e.g. air, enters the device 1 and is there fed to a first inlet 21 of the heat exchanger 3. In the heat exchanger 3, the oxygen-containing gas 19 is heated so that heated, oxygen-containing gas 20 exits a first outlet 22 of the heat exchanger 3. The first outlet 22 of the heat exchanger 3 is connected to a second inlet 23 of the oxygen separation device 5, so that the heated, oxygen-containing gas 20 enters the second chamber 8, i.e. at the retention side 10 of the membrane 6. The MCM membrane 6 now brings about a transport of oxygen from the retention side 10 to the pass-through side 9. Hereby oxygen is removed from the added oxygen-containing gas 20, reducing its oxygen content. At the same time, oxygen is fed into the branched-off waste gas 17, enriching it with oxygen. At a first outlet 24 of the oxygen separation device 5, waste gas 25 accordingly enriched with oxygen exits the first chamber 7 and is fed via a line 26 to a second inlet 27 of the heat exchanger 3. In the heat exchanger 3, the oxygen-enriched, returned waste gas 25 is cooled. Then cooled, enriched waste gas 29 that is also compressed in the compressor 4 exits from a second outlet 28 of the heat exchanger 3. This compressed, enriched waste gas 29 is then fed to an inlet side 30 of the burner 2. The inlet side 30 of the burner 2 is also supplied with fuel or a fuel/steam mixture 31 that reaches the device 1 at 32. In the burner 2, a combustion mixture of the oxygen-enriched, returned waste gases 29 and the added fuel 31 then forms. According to the invention, the burner 2 includes a catalyzer 78 that initiates and/or stabilizes the combustion reaction. During this combustion, the desired hot combustion waste gases 11 are produced.

[0026] At a second outlet 33 of the oxygen separation device 5, oxygen-containing gas 34 that now has a reduced oxygen content, but an increased temperature exits. This oxygen-containing gas 34 exits the device 1 at 35. The oxygen separation device 5 here also functions as a heat exchanger, whereby it should be noted that the flow flows through the two chambers 7 and 8 in the same direction in order to keep temperature loads in the membrane 6 as small as possible.

[0027] In a special embodiment, the burner 2 and the heat exchanger 3 can be combined to form a heat exchanger/burner unit. According to FIG. 2, a corresponding embodiment of the device 1 thus has such a heat exchanger/burner unit 36. The device 1 again has the oxygen separation device 5 that in this embodiment is called the first oxygen separation device 5. The device 1 also contains a second oxygen separation device 37 that also works with an MCM membrane 38 as oxygen separation mean. This membrane 38 divides a first chamber 39 from a second chamber 40 and has a pass-through side 41 exposed to the first chamber 39, and a retention side 42 exposed to the second chamber 40.

[0028] A combustion that produces hot combustion waste gases 11, which exit at an outlet side 87, also takes place in the heat exchanger/burner unit 36. A partial stream 17 of these combustion waste gases 11 is also branched off here and fed into the first oxygen separation device 5. The branched-off waste gases 17 therefore enter the first chamber 7 of the first oxygen separation device 5. The oxygen-enriched waste gas 25 produced there is then fed to an inlet side 43 of the heat exchanger/burner unit 36. In addition, the fuel or fuel/steam mixture 31 is fed to the inlet side 43 of the heat exchanger/burner unit 36.

[0029] The potion of the combustion waste gases 11 not branched off or returned is fed to a first inlet 44 of the second oxygen separation device 37, whereby fuel 45 is also fed to this first inlet 44, which fuel enters the device 1 at 46. This means that a mixture of combustion waste gases 11 and fuel 45 is fed into the first chamber 39, i.e. on the pass-through side 41.

[0030] The oxygen-containing gas 19 entering the device at 18 is greatly heated in the heat exchanger/burner unit 36 and is fed as the heated, oxygen-containing gas 20 to the first oxygen separation device 5. From the latter, the oxygen-containing gas 34 that has been reduced with respect to its oxygen content exits the second outlet 33 and enters through a second inlet 47 of the second oxygen separation device 37 in the latter's second chamber 40 and is then on the retention side 42. The membrane 38 brings about a transport of oxygen from the second chamber 40 into the first chamber 39, so that a combustible mixture forms in the first chamber 39. Because of the high temperatures, a combustion reaction occurs in the second oxygen separation device 37 or in its first chamber 39. The second oxygen separation device 37 accordingly works as a membrane reactor.

[0031] The combustion reaction again causes hot combustion waste gases 48 to form in the first chamber 39, said combustion waste gases exiting through a first outlet 85 of the second oxygen separation device 37 from the first chamber 39, and at 14 from the device 1. The operation of the second oxygen separation device 37 removes even more oxygen from the oxygen-containing gas 34, whereby this gas is at the same time greatly heated due to the reaction in the first chamber 39. The heated, now essentially oxygen-poor gas 49 exits the second chamber 40 through a second outlet 86, and from the device 1 at 35. The flow through the chambers 39 and 40 of the second oxygen separation device 37 in parallel or in the same direction also should be noted here. The selected flow makes it possible to avoid temperature peaks, increasing the useful life of the membrane 38.

[0032] According to FIG. 3, the device 1 according to the invention may be integrated into a gas turbine system 50 that is used to generate electricity. Of the complex construction of the device 1 according to the invention, only the oxygen separation device 5 with the membrane 6 is shown in an exemplary member in FIG. 3. In principle, both the embodiment according to FIG. 1 as well as the embodiment according to FIG. 2 as well as any other desired variation of the device 1 can be implemented in the gas turbine system 50.

[0033] A compressor 51 compresses the ambient air 52. The heated and compressed ambient air forms the oxygen-containing gas 19 that is fed into device 1 at 18. In this device 1, the ambient air is heated, and its oxygen content is reduced. The heated, oxygen-poor air 34 (variation according to FIG. 2) or 49 (variation according to FIG. 2) exits the device 1 at 35 and is fed to a turbine 53 that is connected to a compressor 51 and a generator 54 for electricity generation. The gas 34 or 49 fed to the turbine 53 is expanded in the turbine 53 and forms an expanded flow 55, the heat of which is recovered in a steam generator 56. Then cooled, oxygen-poor gas 69 that can undergo further treatment exits the steam generator 56.

[0034] At 32, fuel or a fuel/steam mixture 31 is fed to the device 1, whereby the fuel inside the device 1—as described above—burns with the oxygen from the oxygen-containing gas 19. The resulting combustion essentially produces only CO₂ and H₂O and forms the desired hot combustion waste gases 11 (variation according to FIG. 1) or 48 (variation according to FIG. 2) that exit the device 1 at 14. The hot combustion waste gases 11, 48 are expanded in a turbine 57 that drives another generator 58 for electricity generation. In the process, expanded combustion waste gases 59 that are also fed to the steam generator 56 form. The steam generator 56 hereby comprises separate chambers 60 and 61 for the expanded, oxygen-poor gases 55 or for the expanded combustion waste gases 59. Then cooled combustion waste gas 62 exits the steam generator 56 and can be fed to a cooler 63 in which the water steam contained in the waste gas 62 is condensed. The resulting water 64 is again fed to the steam generator 56. The remaining CO₂ 65 leaves the cooler 63 and can be compressed and, as the case may be, liquefied, in a compressor 66. The compressed and/or liquefied CO₂ 67 then can be processed further. The compressor 66 is, for example, driven by a motor 68. A coupling with the turbine 57 is also conceivable.

[0035] The steam 70 generated by the steam generator 56 can be expanded in a turbine 71 that drives another generator 72 for electricity generation. The expanded steam then can be condensed in a condenser 73 into water and returned to the steam generator 56. It would also be possible to use the steam 70 as process steam for other purposes; for example, the steam 70 can be mixed with the fuel 31 to form a fuel/steam mixture.

[0036] According to FIG. 4 and 5, the burner 2 (FIG. 4) or, respectively, the heat exchanger/burner unit 36 (FIG. 5) has a fuel oxidator/mixer 74 formed, for example, by an injection nozzle 75 and a Venturi mixing section 76. Alternatively or additionally, a static mixer 77 may be provided. Also provided is a catalyzer 78 that may comprise one or more catalyzer elements. In the example at hand, the catalyzer 78 consists of catalyzer elements 79 and 80 arranged serially. Each of these catalyzer elements 79, 80 is preferably constructed as a monolithic carrier with parallel flow channels and preferably consists of metal oxide. Because of the parallel flow channels, the catalyzer elements 79, 80 and thus the entire catalyzer 78 only have a low flow resistance, so that only a relatively low pressure loss occurs during the flow through the catalyzer 78.

[0037] It is useful that the catalyzer element 79 located upstream with respect to the flow through the burner 2 or the heat exchanger/burner unit 36 consists of a catalyzer material that is more active than that of the catalyzer element 80 located downstream. It is also useful that the downstream catalyzer element 80 is produced from a thermally more stable material than the upstream catalyzer element 79. While the upstream catalyzer element 79 therefore is particularly suitable for an initiation of the combustion, the downstream catalyzer element 80 can be used particularly well for stabilizing the combustion. If there are more than two catalyzer elements 79, 80, one or more upstream catalyzer elements 79 accordingly may be more active and/or more downstream catalyzer elements 80 may be more stable.

[0038] The catalyzer 78 is followed by a stabilizion zone 81 that brings about an aerodynamic stabilization of the homogeneous reaction zone. Downstream from this stabilization zone 81 is a burn-out zone 82, in which the homogenous reaction can be completed.

[0039] According to FIG. 5, a housing 83 in which the actual burner of the heat exchanger/burner unit 36 is constructed is enclosed at least in the area of the catalyzer 78 by a heat exchanger 84 into which relatively cold, oxygen-containing gas 19 enters at 21, and from which relatively warm, oxygen-containing gas 20 exits at 22. This results in a particularly compact construction for the heat exchanger/burner unit 36.

List of Reference Numbers

[0040] 1 device 2 burner 3 heat exchanger 4 compressor 5 first oxygen separation device 6 oxygen separation mean, MCM membrane of 5 7 first chamber of 5 8 second chamber of 5 9 pass-through side of 6 10 retention side of 6 11 hot combustion waste gas 12 outlet side of 2 13 waste gas line 14 outlet point of 1 15 return line 16 first inlet of 5 17 branched-off waste gas 18 inlet point of 1 19 oxygen-containing gas 20 heated oxygen-containing gas 21 first inlet of 3 22 first outlet of 3 23 second inlet of 5 24 first outlet of 5 25 oxygen-enriched, branched-off waste gas 26 line 27 second inlet of 3 28 second outlet of 3 29 cooled, charged, enriched, branched-off waste gas 30 inlet side of 2 31 fuel/steam mixture 32 inlet point of 1 33 second outlet of 5 34 oxygen-reduced gas 35 outlet point of 1 36 heat exchanger/burner unit 37 second oxygen separation device 38 oxygen separation mean, MCM membrane of 37 39 first chamber of 37 40 second chamber of 37 41 pass-through side of 38 42 retention side of 38 43 inlet side of 36 44 first inlet of 37 45 fuel 46 inlet point of 1 47 second inlet of 37 48 hot combustion waste gas 49 hot oxygen-poor gas 50 gas turbine system 51 compressor 52 ambient air 53 turbine 54 generator 55 expanded, hot oxygen-poor gas 56 steam generator 57 turbine 58 generator 59 expanded, hot combustion waste gases 60 first chamber 61 second chamber 62 expanded, cooled combustion waste gases 63 cooler 64 liquid water 65 CO₂ gas 66 compressor 67 compressed and/or liquid CO₂ 68 motor 69 cooled, expanded, oxygen-poor gas 70 water steam 71 turbine 72 generator 73 condenser 74 fuel oxidator/mixer 75 injection nozzle 76 Venturi mixing section 77 static mixer 78 catalyzer 79 first catalyzer element 80 second catalyzer element 81 stabilization zone 82 burn-out zone 83 housing 84 heat exchanger 85 first outlet of 37 86 second outlet of 37 87 outlet side of 36 

1. Method for producing hot combustion waste gases, in particular for a gas turbine system, wherein a combustion takes place in a burner (2; 36) that produces the hot combustion waste gases (11), wherein a portion of the combustion waste gases (17) is branched off and fed to a first inlet (16) of an oxygen separation device (5), wherein an oxygen-containing gas (20) is fed to a second inlet (23) of the oxygen separation device (5), wherein the oxygen separation device (5) has oxygen separation means (6) that remove oxygen from the oxygen-containing gas (20) and feed said oxygen to the branched-off waste gas (17) and in this way reduce the oxygen content of the oxygen-containing gas (20) and produce oxygen-enriched, branched-off waste gas (25), wherein the oxygen-enriched, branched-off waste gas (25) as well as a fuel (31) or a fuel/steam mixture are fed to the burner (2; 36) and form a combustion mixture that burns in the burner (2; 36) while forming the hot combustion waste gases (11), characterized in that the combustion in the burner (2; 36) is catalytically initiated and/or stabilized.
 2. Method as claimed in claim 1, characterized in that the oxygen-containing gas (20) is heated prior to its entrance into the second inlet (23) of the oxygen separation device (5).
 3. Method as claimed in claim 1 or 2, characterized in that a second oxygen separation device (37) is provided, whereby the non-branched-off portion of the hot combustion waste gases (11) as well as the fuel (45) or a fuel/steam mixture are fed to a first inlet (44) of the second oxygen separation device (37) and form a mixture, whereby the oxygen-containing gas (34) whose oxygen content has been reduced is fed to a second inlet (47) of the second oxygen separation device (37), whereby this second oxygen separation device (37) also is provided with oxygen separation means (38) that remove even more oxygen from the oxygen-containing gas (34) and feed it into the mixture, whereby on the one hand the mixture with the oxygen burns and produces hot combustion waste gases (48), and on the other hand a gas (49) that is yet again reduced with respect to its oxygen content and heated is produced.
 4. Device for producing hot combustion waste gases, in particular for a gas turbine system, with a burner (2; 36) whose outlet side (12; 87) is connected to a waste gas line (13), from which a return line (15) branches off, and with an oxygen separation device (5) whose first inlet (16) is connected with the return line (15), and whose second inlet (23) is connected to a gas supply that supplies oxygen-containing gas (20), whereby the oxygen separation device (5) is provided with oxygen separation means (6) that remove oxygen from the oxygen-containing gas (20) and feed it to the branched-off waste gas (17), whereby the oxygen separation device (5) is provided with a first outlet (24) for oxygen-enriched, branched-off waste gas (25) and a second outlet (33) for gas (34) whose oxygen content has been reduced (34), whereby an inlet side (30; 43) of the burner (2; 36) communicates with the first outlet (24) of the oxygen separation device (5) as well as with a fuel supply that supplies fuel (31) or a fuel/steam mixture, characterized in that the burner (2; 36) comprises a catalyzer (78) that initiates and/or stabilizes the combustion.
 5. Device as claimed in claim 4, characterized in that a second oxygen separation device (37) has been provided, whose first inlet (44) communicates with the waste gas line (13) and with a fuel supply that supplies fuel (45), a second inlet (47) of the second oxygen separation device (37) communicates with the second outlet (33) of the first oxygen separation device (5), the second oxygen separation device (37) is provided with oxygen separation means (38) that remove even more oxygen from the oxygen-containing gas (34) and feed it to the mixture of fuel and (45) and combustion waste gases (11), whereby on the one hand the mixture with the oxygen burns and produces hot combustion waste gases (48), and on the other hand a gas (49) that is yet again reduced with respect to its oxygen content and heated is produced., the second oxygen separation device (37) is provided with a first outlet (85) for the hot combustion waste gases (48) and a second outlet (86) for hot, oxygen-poor gas (49).
 6. Device as claimed in claim 4 or 5, characterized in that the catalyzer (78) is constructed as a metal oxide catalyzer.
 7. Device as claimed in one of claims 4 to 6, characterized in that the catalyzer (78) is provided with a monolithic carrier with parallel flow channels.
 8. Device as claimed in one of claims 4 to 7, characterized in that the burner (36) is connected in a heat-transferring manner with a heat exchanger (84) that heats the oxygen-containing gas (19) prior to its entry into the oxygen separation device (5).
 9. Device as claimed in one of claims 4 to 8, characterized in that at least one of the oxygen separation devices (5; 37) has a first chamber (7; 39) and a second chamber (8; 40), the oxygen separation devices (6; 38) are provided with a membrane that divides the two chambers (7, 8; 39, 40) from each other and transports oxygen from one chamber (8; 40) into the other chamber (7; 39), both chambers (7, 8; 39, 40) are passed by the flow in the same direction and parallel to the membrane.
 10. Device as claimed in one of claims 4 to 9, characterized in that the burner (2; 36) is provided with a burn-out zone (82) downstream from the catalyzer (78),
 11. Device as claimed in claim 10, characterized in that the burner (2; 36) is provided between the catalyzer (78) and the burn-out zone (82) with a stabilization zone (81).
 12. Device as claimed in one of claims 4 to 11, characterized in that the catalyzer (78) is provided with one or more serially arranged catalyzer elements (79, 80).
 13. Device as claimed in claim 12 or 13, characterized in that at least one upstream catalyzer element (79) consists of a more active catalyzer material than at least one downstream catalyzer element (80).
 14. Device as claimed in claim 12 or 13, characterized in that at least one downstream catalyzer element (80) consists of a thermally more stable catalyzer material than at least one upstream catalyzer element (79). 